Preach to the choir意思

"Preach to the choir" is an English idiom that means to give information or an opinion to people who already agree with it or are already knowledgeable about it. The "choir" in this expression refers to a group of people who share the same beliefs or opinions as the speaker. The idea is that it's unnecessary or redundant to preach to the choir because they are already convinced and there is no need to persuade them.

For example:

"The politician's speech about the importance of environmental conservation was preaching to the choir; everyone at the green energy summit already believed in those principles."

In this context, the phrase implies that the effort could have been better directed towards people who might not yet be convinced or informed, rather than those who are already aligned with the message.